[EM] Rank methods, participation, consistency

[MIKE OSSIPOFF]

Most rank methods, even if monotonic, fail Participation & Consistency.

Borda is the only rank method that I know to pass those 2 criteria.
I'm not saying there couldn't be one that I don't know of.

I don't want that to sound like an endorsement of Borda, which I
consider the _worst_ single-winner method. But when short rankings
are allowed, as in the Slovenian system, Borda isn't nearly as bad,
though it still isn't as good as CR & Approval. CR is a natural
improvement on Borda, allowing the voter to give whatever point score
he wants to a candidate, without the limitation that Borda imposes
on those points assignments. If voters were interested only in
helping maximize social utility by voting sincerely, and not in
opimizing the outcome for themselves, and if they wanted to rank
rather than to rate, then Borda would be one good choice for their
voting system.

Speaking of Borda, it's a method that, while it passes Participation
& Consistency, fails IIAC, as I define it, and probably as anyone
else defines it.

I don't know of any method that meets one of the 2 criteria Participation & 
Consistency without meeting the other.

Mike Ossipoff


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